Emptiness is a key concept in Buddhist philosophy, or more precisely, in the ontology of Mahayana Buddhism. The phrase "form is emptiness; emptiness is form" is perhaps the most celebrated paradox associated with Buddhist philosophy. It is the supreme mantra. The expression originates from the Prajna Paramita Hridaya Sutra, commonly known as the Heart Sutra, which contains the philosophical essence of about six hundred scrolls making up the Maha Prajna Paramita. The Heart Sutra is the shortest text in this collection. It belongs to the oldest Mahayana texts and presumably originated in India around the time of Jesus Christ.

Emptiness of emptiness.

In The Art of Living (2001) the 14th Dalai Lama says, "As your insight into the ultimate nature of reality is deepened and enhanced, you will develop a perception of reality from which you will perceive phenomena and events as sort of illusory, illusion-like, and this mode of perceiving reality will permeate all your interactions with reality. [...] Even emptiness itself, which is seen as the ultimate nature of reality, is not absolute, nor does it exist independently. We cannot conceive of emptiness as independent of a basis of phenomena, because when we examine the nature of reality, we find that it is empty of inherent existence. Then if we are to take that emptiness itself is an object and look for its essence, again we will find that it is empty of inherent existence. Therefore the Buddha taught the emptiness of emptiness."